


RCA: Root Cause Analysis

by justanexercise



Category: How I Met Your Mother, Marvel Cinematic Universe, Person of Interest (TV)
Genre: Alternate Universe, Crossover, F/F
Language: English
Status: Completed
Published: 2015-08-28
Updated: 2015-08-28
Packaged: 2018-04-17 15:21:27
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,908
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4671563
Author URL: https://archiveofourown.org/users/justanexercise/pseuds/justanexercise
Summary: <blockquote class="userstuff">
              <p>Natasha pulls in a favor from a friend to take care of Ted once and for all. (Prompted by Littlesolo)</p>
            </blockquote>





	RCA: Root Cause Analysis

**Author's Note:**

  * For [littlesolo](https://archiveofourown.org/users/littlesolo/gifts).



“Why’s your office so dark?”

Natasha puts the bag of takeout onto Maria’s desk and reaches for the remote to deactivate the tinted windows.

“Don’t,” Maria says, grabbing onto Natasha’s wrist.

“Okay.” Natasha relaxes her arm and Maria drops it. “What’s wrong?”

Leaning back onto her ergonomic chair, Maria rubs the bridge of her nose.

“Have you gone outside? Looked outside?”

“Yes,” Natasha says, tilting her head, “What’s outside?”

“Did you go through the front door?”

“Course not, paparazzi and Stark fangirls, remember?”

Maria shudders. Yes, yes she does remember. Incident #138, involving silly string, lots of pretty girls and Pepper almost killing Tony. And a PR disaster that not even SHIELD training prepared her for.

“See for yourself.” Maria tosses Natasha the remote.

Natasha opens one panel of the window, peering out. She clenches her jaw.

“How long have they been out there? Do those instruments even work?”

“Apparently they do, I’m hoping that if they get loud enough they’d get arrested.”

Natasha puts on the privacy settings once more, the room going dark. She turns on the overhead lights for Maria. “Why haven’t you called the cops on them?”

“I did, they have permits and everything. You’d think an entire marching band bellowing on the streets would be cause for public disturbance.”

“I could –“

“No.”

Natasha’s face drops. “You don’t even know what I was going to say.”

“Were you going to offer to maim, torture, kill, abduct or ruin Ted in any way?”

“No.” Natasha’s cheek twitches.

“Uh huh.” Maria shakes her head and points to the takeout bag.

“What’s this?”

“Park’s Deli,” Natasha says with a grin.

Maria grins, ripping open the brown bag and snatching up the sandwich. She moans at the first bite.

“You are amazing,” Maria says with her mouth full.

Kissing Maria on the cheek, Natasha turns to leave her office.

“You’re not staying?”

“Just came by to drop off your lunch, you forgot to eat.”

“Keeping tabs on me again?”

“You’d go hungry if I didn’t.”

Natasha blows Maria a kiss, stepping out into the hallway. Her smile drops. She types a number on her phone, thumb hovering over the green call button. The loud sounds of the band penetrating even through the expensive Stark designed building solidify her resolve. She makes the call.

“I need a favor,” Natasha says once the phone connects.

There’s a pause on the line, Natasha narrows her eyes, practically seeing the smirk on the caller’s face.

“Anything for you _lisichka_.”

Natasha shakes her head, a slight smile ticking across her face at the nickname.

-

“I hope he’s the perp.”

Shaw looks through her binoculars, watching as their new number enters a flower shop.

“Ted Mosby,” Finch says through the comms, “Architect, greatest achievement to date is the GNB building. Divorced with two children.”

“Think it’s the ex?” Reese asks, leaning forward in the passenger seat to get a better look.

“He designed the GNB building, I’m going to shoot him first,” Shaw grumbles.

Reese raises an eyebrow.

“I’ve tracked his GPS coordinates for the past week, Mr. Mosby has been spending a copious amount of time outside the Avengers Tower,” Finch says.

Shaw lowers her binoculars.

“Think he’s planning on something then?”

“It’s possible, he requested architectural designs to the tower from colleagues. Though no one has them, Pepper Potts keeps a tight rein on those matters it seems.”

“Smart woman,” Shaw says.

Exiting the car, Reese and Shaw tail Mosby on foot, bluejacking his phone as the three of them wait at the crosswalk.

“Shouldn’t his number have gone to the relevant side if he were planning an attack?” Reese asks.

“If he’s the perpetrator it could be on a more personal level.”

Shaw nods in agreement.

“He reeks of ‘nice guy’ syndrome.”

Following him for a few more blocks, Reese and Shaw narrow their eyes and pick up their distance.

“Finch, he’s headed to the tower,” Reese says.

Shaw takes off to the other side of the street, hand in her coat pocket, gun in hand.

Mosby sends a mass text, Shaw seeing it in real time.

 **[Mosby]  
** Operation Love Signage is a-go.

“Harold? Whatever it is, it’s happening now.”

“He sent the text to over twenty people,” Finch says. “I can’t trace them all, but the cellphone towers all pinged in your area, it’s happening near you.”

Shaw pulls out her gun, clicking off the safety. Wading her way through young adults, she shoulders past them as they carry blue instruments. She keeps her eyes trained on him, assessing the danger around them. He steps to the front of the gathered crowd and unfurls a large banner.

I MISS YOU ROBIN.

Shaw disappears to the side of the crowd, next to Reese.

“He’s declaring love in public,” Shaw says with distaste.

“He has an entire flock of romantics bellowing out a tune, on blue instruments,” Reese says, snapping pictures and sending them to Finch.

“I’d need some time to hack into the Stark personnel files to find anyone named Robin. It would be easier to follow Mr. Mosby and see who he interacts with.”

Shaw shakes her head, going through Mosby’s phone calendar. She frowns.

“Harold, this is the 5th time this week he’s pulled this stunt.”

“He seems rather…persistent.”

“I’ve seen guys like this Harold, they don’t get what they want, they’ll start resorting to other things. Violent things. We can take him out of the equation before he escalates.”

“Ms. Shaw, please we don’t know if he is the perpetrator yet.”

Shaw grinds her heel to the ground.

“Fine.”

-

Taking a ferocious bite out of her hot wings, Shaw glances over at the booth where Mosby and his friends are. Lily and Marshall.

“Any developments?” Finch asks them through their ear piece.

“Mosby is desperate to win back this Robin, the Erikson’s are trying to persuade him out of it,” Reese says. He takes a look at the discarded bones on the table and pushes his napkin towards Shaw. “And Shaw likes her wings Diablo Hot.”

“What?” Shaw asks, wiping her mouth with the back of her hand.

“Getting ready to shoot someone?”

Shaw grins. “Can’t expect me to shoot someone on an empty stomach.”

Both Shaw and Reese’s smiles widen at Finch’s exasperated sigh.

“I’ve found many references to a Robin Scherbatsky from 2005 to 2014, but her appearance in their lives seem to cease after that. No more contact, she quit her job, moved to Europe.”

“You don’t sound so sure Finch,” Shaw says. “Thinking this guy killed Scherbatsky?”

“Wouldn’t explain why he’s courting a Robin now though,” Reese answers.

“Another Robin?”

“I’m sending a picture of her now,” Finch says.

Reese raises his eyebrows and looks back over to Mosby. “She’s pretty, out of his league though.”

“Could be he graduated from menace to killer,” Shaw says. She narrows her eyes, studying Scherbatsky’s picture with a critical gaze. “She look familiar to you?”

Reese nods in agreement.

“He’s leaving,” Shaw says and Reese pulls out cash to cover Shaw’s dinner and his soda.

While they follow him through the streets, Shaw notes the other man tracking Mosby’s movements like them. Shaw points her chin to the man in a sport coat. Reese nods. Understood.

She breaks away, going through an alternate route.

Mosby rounds the corner, blind spot for cameras, the man speeds up his walk, his hand flicking open a syringe.

Reese soundlessly steps behind the man, knocking his forehead into a lamp post and kicking the syringe out of his closed fist.

“What the hell?” Mosby shrieks, spinning around.

The downed man shoves Reese away and advances on Mosby, knife out from his belt.

Luckily for Mosby, Shaw pushes Mosby to the ground and breaks the man’s nose before he can rip Mosby a few new holes. Reese finishes the blow with a trashcan lid.

“What was that?” Mosby points to the unconscious man. “Who are you? What was that?”

Shaw rolls her eyes so hard they threaten to stay that way. She waves her hand towards Mosby. “Your turn,” she says to Reese.

“No, I got the freaked out housewife a week ago, it’s your turn.”

“And I got the kid four days ago, who by the way bit me.”

Reese exhales, turning to a still freaked out Mosby pointing an accusing finger at them. “Mr. Mosby, you’re in danger.”

“You think?!”

“We can take you someplace safe, but for now, you have to trust us.”

Mosby studies them, his eyes squinting in the dark. “This is her plan isn’t it? You guys look like ex-military, or should I say, SHIELD?” He stands up, brushing himself off. “She put you up to this didn’t she? I knew she still cared!”

Shaw blinks. “Good luck John.” She steps back but Reese puts his hands up.

“Shaw…you can’t leave me with this.”

“It’s your turn,” Shaw sing-songs.

“I’m afraid you both can’t leave him alone,” Finch says to them. “I just found out who Robin Scherbatsky is. Maria Hill, she was SHIELD, Assistant Director, now working for Tony Stark as his head of security.”

Shaw whirls around to Mosby, eyes narrowing at his posturing to her height. “You’re stalking Maria Hill who’s arguably one of the most powerful and deadly women on this planet?”

“Robin, and it’s not stalking,” he points out.

Shaw shakes her head, stepping away from him in case she strangles him. “Hill didn’t put out a hit on him.”

“She’s the most qualified for it Ms. Shaw and –“

“If she did, he’d be dead and no one would ever know. Not even us.” Shaw kicks at the unconscious man, rifling through his pockets. Nothing. “This guy, amateur. No ID on him though, so someone knew that.”

“Robin would never try to kill me!” Mosby says, pushing past Reese’s arm. “No Robin wouldn’t,” he mutters, “but _she_ would.”

“Who’s she?”

“She knew Robin still loved me, and she’s trying to take out the competition! Well the tables have turned, I’m still alive and now I know what she did.” His eyes glitter, looking back and forth between Shaw and Reese. “And I have two witnesses. Oh you little spider you picked the wrong fight.”

“Harold, have you ruled out that he’s insane?”

“Mr. Mosby has no record of having any mental illness, though I’m beginning to wonder about that.”

Shaw raises her head, searching around the block. “Where’d he go?”

Reese does a full body turn, no Mosby in sight. “Shit.”

“I have him,” Finch says, “His phone is still on, he seems to be…oh dear, he’s heading back to the Tower.”

“I’m knocking him out the first chance I get,” Shaw mumbles, breaking into a car.

Reese climbs into the passenger seat, grabbing onto the handrail first.

“Hey kids.”

Shaw swerves the car when her comms flare back to life.

“Root.”

“Heard you lost something.”

Shaw executes a perfect parallel parking, right in front of Root and Mosby sitting on a bench, him slumped to the side.

“What are you doing here?” Shaw asks as she gets out of the car.

Reese checks Mosby’s pulse, still alive. He raises an eyebrow at the taser marks on Mosby’s neck.

“What’s Ms. Groves doing there?” Finch asks them.

Root perks up, smirking and sliding right into Shaw’s space. “Hey Harry, heard you had a little runaway problem, I was in the neighborhood.”

“We should get him to a safehouse,” Reese says, hoisting Mosby up and stashing him in the trunk of their stolen vehicle.

Clasping her hands in front, Root says, “Well, you two have it well in hand now, try not to let this one loose again.”

Shaw grabs Root’s wrist before she can step away. “Did you do it?”

“You’re going to have to be a little more specific than that.”

Shaw stares.

Root leans in again, practically hovering her lips over Shaw’s. “I love it when you play interrogator.”

Shaw grunts, throwing Root’s arm back at her and stomping away. Root had something to do with it. Shaw glances at the spot she left Root, course she’s not there.

-

Mosby pulls on his restraints, hands banging on the table. “She hired you didn’t she? She hired you to get rid of me?”

“Mr. Mosby,” Finch says, exasperation clear in his voice and slouch. “Who do you think hired us?”

“Playing dumb now? I see how it is, oh I see it all. Robin doesn’t know does she?” His head jerks around. “ROBIN!”

“Can we just tase him again?” Shaw asks, hands rubbing delicately at her temples.

“Hold on,” Mosby holds his hands up. “No need to be hasty.”

“Now can we have a civilized conversation?” Finch asks.

Mosby nods yes.

“Who do you think is trying to kill you Mr. Mosby?”

Squinting his eyes at Finch, Mosby turns to study Shaw and Reese, coming to the absolute wrong conclusions. “You’re trying to see how much I know, how much I know about _her_. Well that tactic isn’t going to work on me!”

“Okay times up,” Shaw says, cracking her knuckles. “Can we just throw him in the funny house? He’s a danger to himself.”

“So that’s the plan,” Mosby says, smug. “They’ll be looking for me if I don’t turn up. And I’ll tell the world about what she’s done to me.”

“Who’s she?” Reese asks.

“I’m not –“

Reese cocks his gun. “Who. Is. She?”

Mosby swallows, staring at the loaded gun. “The Black Widow.”

The room goes still.

Shaw spins on her heels and walks up to the door. “You boys are on your own.”

“Ms. Shaw,” Finch tries to reel her back in.

“Hey, we already saved his life, I think that’s mission accomplished, you never said anything about delusional numbers.” Shaw shoots Reese a grin. “Have fun.”

Reese deflates as Mosby protests once more and Shaw shuts the door, drowning him out.

She’s got another crazy to attend to, this one far more fun.

-

“Did you do it?” Shaw asks, staring at the ceiling.

Root shuffles next to her, the sheet slipping from her torso. Shaw spares her a glance, smirking at the red bite marks across her pale skin.

“Do what?” Root asks, sitting against the headboard.

“You tell me.”

“Sweetie, I may have an all-seeing God in my ear, but She can’t read minds.”

“Mosby.”

“Your number? Well I did tase him,” Root says, running her toe along Shaw’s thigh under the sheet. “Why? Did you want some electricity tonight?”

Shaw grunts, moving her leg closer to Root. “The hit was terrible, didn’t even break a sweat. Fusco’s got him in lockup. Says he got an e-mail and $5000 wired to his account to kill him.”

“And you thought of me? I’m offended.” Root leans in tracing the bridge of Shaw’s nose with her finger. “If I wanted him dead, he’d be dead.”

Shaw grabs her wrist, pulling her down on top of her. “Why don’t you?”

Root hums in question, licking her lips, her body stretching on top of Shaw’s.

“Suggested Harold send him to the funny house,” Shaw says.

“Uh huh.” Root tucks her head into Shaw’s neck, kissing and biting until Shaw rolls them over, pinning Root’s hands above her head.

 

The next morning, Shaw awakens with the sound of a text. She huffs and rolls out of bed, grabbing the phone off the night stand. Her eyes narrow into slits at the phone preview. It’s not her phone.

 **[Lisichka]**  
Thanks. Lunch is …

Shaw puts the phone back at the sound of a flushing toilet, she stretches and digs through her drawer for a new set of clothes. She barely gives Root a glance as she comes back to the room, fully dressed. Root slides her fingers across Shaw’s naked waist before retrieving her phone.

“Gotta go Sam,” Root says, waving from the doorway.

Hurriedly putting on her clothes, Shaw peers out of her window, watching Root ride into traffic on her motorcycle. Shaw smirks, good thing she put a tracking device on the motorcycle.

-

“Sameen,” Root says, kicking out a chair for her. “Would you like to join us?”

Shaw takes a seat next to Root, she eyes the steak, perfectly grilled in front of her. She raises a questioning eyebrow at Root.

“What? You didn’t think I knew about the tracker?”

Shaw turns her attention to the other woman, or more accurately, Natasha Romanoff, the Black Widow. “Lisichka, Little Fox? Really?”

Natasha shrugs, stirring her mimosa in her manicured hand. “Old nickname.”

“So he wasn’t delusional,” Shaw says, cutting into her steak.

“Arguable,” Natasha says.

“How do you two know each other?”

Root sighs wistfully, sending Natasha a look of utter adoration. Natasha grins, fluttering her eyelashes. Shaw grips her knife tighter.

“It’s a long story,” Natasha answers.

Shaw rips off a piece of steak, chewing loudly. “And?”

“And,” Root leans her chin on her hand, “how do you feel about invading a HYDRA base upstate?”

Shaw raises an eyebrow.

“How do you feel about rockets Shaw?” Natasha asks.

Shaw’s hand twitches. She grins, leaning back in her chair. “Just one question.”

Natasha nods her go ahead.

“Did you get her into tasers?” Shaw asks, pointing to Root.

Root chuckles while Natasha’s face turns into a blank slate.

“You have it the other way around Sam.”

It clicks. Shaw’s jaw drops. “No way.”

“Sorry honey, you weren’t the first assassin I tased on first meeting.”


End file.
